1. Field of the Invention
The present invention relates to improvements in a seat adjuster which comprises a seat slide mechanism and a seat lifting mechanism.
2. Description of the Prior Art
A variety of seat adjusters have been proposed and in practical use. FIGS. 4 and 5 show a typical seat adjuster which has a pair of lower base members 2 fixed to a seat side rail 1 and a pair of upper base members 4 fixed to a seat cushion fame 3. Front and rear shaft members 5 and 5a are laterally disposed at front and rear ends of the lower base members 2, respectively. Front and rear supporting links 6 and 6a are connected with the shaft members 5 and 5a, respectively. Two output shafts 7a of a drive unit 7 is connected with the shaft members 5 and 5a through transmission links 8 and 8a, respectively. The supporting links 6, 6a and the transmission links 8, 8a are formed in different shapes between the front and rear parts.
FIGS. 6 and 7 show another conventional seat adjuster. In this seat adjuster, a pair of base members 2 are fixed on a pair of seat side rails 1. Front and rear shaft members 5 and 5a are laterally disposed at front and rear ends of the base members 2, respectively. Each one end of each relay link 9, 9a is connected to each output shaft 7a of a drive unit 7 and swingably supported to each of the front and rear shaft members 5, 5a. Each supporting link 9b, through which the seat adjuster is fixed to a seat cushion frame 3, is supported to the other swinging end of each relay link 9, 9a. Similarly, in this seat adjuster, the relay links 9 and 9a are formed in different shapes, respectively.
Thus, the conventional seat adjusters are generally formed by using various link members which are formed in different shapes between the front side and the rear side, as shown in FIGS. 4 to 7. Furthermore, these seat adjusters are constructed such that various links of the adjuster are integrally interconnected with the base member to form a lifter unit and that the base member of the lifter unit is fixed to the seat rail and/or the seat cushion frame. Accordingly, this prevents the seat adjuster from being formed smaller and lighter. Accordingly, the manufacturing cost of these seat adjusters becomes high.